


Tide Rising

by Colt_kun



Category: Kingdom Hearts
Genre: Alpha Riku, Alpha/Beta/Omega Dynamics, Background M/F/M, Canon Compliant, He gets better, M/M, Multi, Non-ABO character, Omega Sora, Pre-Relationship, Riku (Kingdom Hearts) Has Issues, background F/F, future Poly relationship
Language: English
Status: In-Progress
Published: 2019-04-21
Updated: 2019-08-17
Packaged: 2020-01-23 09:28:18
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply, Underage
Chapters: 4
Words: 4,747
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18546997
Author URL: https://archiveofourown.org/users/Colt_kun/pseuds/Colt_kun
Summary: Riku didn't notice when his own scent began to change. He notices, however, when Sora's does.Canon compliant to all games, no KH3 spoilers thus far.The ABO AU with surprisingly little to no sex (yet.)





	1. Chapter 1

Riku's Mother figured it out first. He came in from a rough round of blitz ball to get a drink and passed her on route to the fridge. Her nose wrinkled. He looked back at her with raised eyebrows as he opened the orange juice carton and moved to drink straight from it.

She swiftly took the juice away, but rather than gripe about being raised in a barn per usual, she poured him a glass and asked, "Riku, maybe it's time you started using some neutralizers?"

He smelled his shirt, but could only detect the usual sea salt spray and hot sweat smell. He shrugged as he drank. 

That night Riku found two new bars of soap and a pack of scent neutralizers in his bathroom. He sniffed them but couldn't really tell any difference other than the vague soapy-clean scent. But his Mother and Mom both seemed able to tell if he used them or not, and insisted.

The last semester of school was awful. Riku's legs hurt all the time as he put on an inch, then swiftly another. He grew taller than his friends, even Wakka who already presented. His uniforms became too tight across the shoulders and too high above his sock line. One morning as he looked in the mirror to tie his tie he noticed his arms - which had been thickening - started to form dips and raises of muscle.

And the smells.

Riku felt he finally understood when people complained of congestion. Suddenly his nose could pick up on the mustiness of incoming rain, the tang of ozone before lightning, the sharpness of the citrus in the unripe paopu fruit he experimentally tried. By himself, of course. He expected an orange taste, or even a lemon like one. The slightly green paopu stung his tongue with bitterness and left a strangely metallic taste in his mouth. He choked and had to spit it out.

Footsteps clattered over the wooden bridge behind him and in a fit of panic, Riku tossed the paopu into the sea. He could still see it for a bit through the crystal water before the ocean reclaimed it.

"Rikuuuu!"

Sora's exuberant voice carried on the wind and Riku turned to see him waving from the dock.

When he saw Kairi right beside the brunette, Riku felt jealousy swell and surprised himself. A lot of his feelings lately were surprising him. His Mom called it his inner Alpha, while his Mother told him that was a stupid myth people used to excuse their actions. Then they teasingly argued about it over dinner.

He was broken from his thoughts when Sora said, "Tidus and Wakka want to play blitz ball but Selphie won't play unless its 3 on 3."

Wakka had his ball out already - the one signed by Tidus' professional player father - and they traced out the vague court into the sand. The game was normally played in a suspension arena, so on land a court was needed instead.

Selphie didn't really enjoy playing. And Tidus always played better offense and ignored defense, so with both of them on his team Riku had to work extra to play defense. Wakka looked extra smug as Kairi aggressively went after the ball and whooped loudly with each point.

Summer started in full swing far too early on the islands. Sweat soaked the collar and armpits of his shirt, overpowering the neutralizer. He could smell himself, and judging by how Wakka's nose twitch at water break midgame, so could he.

Wakka grinned at him. "Congrats man," he quipped, punching Riku's shoulder. "I figured you'd join the A-team."

Tidus gave an unhappy grumble. The kid never liked being anything but first in... well, anything.

"What...?" Kairi gave a confused look to Riku.

"He's presenting, silly," Selphie said. She put up her hand for a high five, though Riku felt a little embarrassed to do it. "Riku's a big tough Alpha now!"

"Oh," Kairi gave an uncomfortable laugh as her hand went to her smooth and slender neck.

"I saw you were getting some muscle-" Wakka's arm wrapped around his neck, pulling him down. Riku's hackles rose and he jerked to get upright, twisting to snag Wakka's waist-

In a moment they were on the ground, arms and legs tangled together as Riku broke Wakka's hold and flipped him. He vaguely heard Kairi's shriek, and a bored "dominance issues" from Selphie as Wakka kicked and fought to throw Riku's weight off. All the gym rules for wrestling were out the window.

Wakka had caught Riku's leg with his own and locked it. He had Riku's shoulder pinned down and that inner part of him growing stronger each day screeched in rage. He would not show throat- he would NOT-

Tidus threw himself on Wakka's back, laughing a bit, and distracted the bigger boy just long enough for Riku to twist free. Sora joined in the fray as well, and it just became a pile of knees and elbows and yelps and laughter and maybe a few growls-

Then Sora was looking up at Riku laughing breathlessly with Riku's hand around one wrist and his forearm bracing Sora's shoulders down. Riku's entire body thrummed with thrill of the struggle-

Tidus' pained shriek broke through when Riku's head was bent over Sora's neck. He could see the small area of skin slightly darker than the rest right in front of him. "STOP!" Tidus' voice reverberated.

Hastily he let go as Sora immediately moved to sit up and look at Tidus. Tidus' fingers dripped blood as he clenched his nose. "I'm so sorry man!" Wakka yelped.

"The first aid kit is in the hut-" Kairi ran off.

Riku's breath came in short hard pants as Selphie and Sora both moved to Tidus' side. Riku could smell distress and Wakka looked perfectly chastised as he moved to touch Tidus' shoulder. "Don't touch me-" Tidus snapped as the area around his eyes started to swell and Wakka's hands flew off-

And despite all that, Riku's pants were still too tight.

Tidus wasn't in school the next day. Or the day after that. ...or after that.

Riku thought that was an unusually long time even for Tidus' image-obsessed celebrity father to keep his son home for a broken nose.

When the bell rang and they were packing up their bags, the teacher asked Sora if he wouldn't mind dropping Tidus' work packet off at his house.

Tidus was usually the second stop on their walk home but Wakka felt contrite enough to walk over with them to the blonde's house.

"I guess I should say sorry again," Wakka said sheepishly. "Maybe he broke something else."

"Any of you could have broken anything," Selphie scolded, swinging her bag to swat Wakka's back.

Sora rang the bell, and Tidus' mom - a pretty blonde woman who Riku heard his Mom calling "a trophy omega", and he never really forgot about it - answered the door. "We brought Tidus his homework-" Sora started but her eyes immediately went to Wakka and then Riku, nose twitching.

"You need to leave," she declared. "I mean. I don't want to be rude but you two-"

"Mom?" Came from behind her. And Riku could smell it.

"Tidus, sorry to bear bad news but we brought your homework!" Sora called.

Couldn't they smell it? Riku stepped away instinctively as Tidus moved from under his mom's arm. A weird metal thing cover his nose and black ridged around his eyes, and he looked exhausted and haggard.

His mom pushed him back inside, stepping forward to shut the door hard behind her. She took the packet from Sora. "Thank you," she said with a withheld sigh. "Tidus won't be feeling well for another few days."

Riku had to step back again because the smell clung to her clothes. Wakka, on the other hand, only stepped closer. "I'm sorry but you need to leave," she told them all, but eyed Wakka hard.

"Tell Tidus we hope he feels better soon," Kairi said politely despite the woman's abrupt dismissal. Sora echoed the sentiment as Selphie pushed hard on Wakka to get him to move away. Still, Riku noticed Tidus' mom didn't moved to re-enter the house until they were well down the block.

"I wonder what Tidus' dad is going to say," Riku said as they walked to where their group usually split. "He isn't going to be happy his only son is presenting as an omega."

Kairi gave a frustrated sigh. "That's so stupid."

"Kairi, does no one in your world have secondary genders?" Sora asked.

"I don't remember," she replied flatly. "Bye guys." She turned down the street and nearly left Selphie behind.

Sora shrugged and looked up at Riku. "Race you to the sandbar!" he announced cheerfully, then took off.

"Hey-!" Riku started, then chased after him.

But that night as Riku looked out the window, he wondered about what Sora asked. Other worlds. What were people like, if they didn't have heats and ruts interrupting their lives? More people like Kairi? Like that stranger on the beach? Worlds without an ocean?

The next day he brought up the raft.


	2. Chapter 2

Tidus was back in class a few days later with sickly brown-yellow bruises around his eyes like a raccoon, looking more annoyed than anything. "Not a word," he snapped when he saw Riku waiting with Wakka. Riku knew the chalky smell of new suppressants now, but a sour tint lingered underneath. Tidus seemed determined to remain unhappy for as long as possible, which lasted until Sora picked him first for his team in a math drill.

Then came the dreaded end of year health class.

"Back before the Secondary Equality Rights Act, once an omega presented they could be claimed by an alpha, usually through an arranged marriage by the omega's dominant parent," the recorded voice sounded way too perky for the subject matter, "and it was believed that the tearing of the omega's outer membrane was their alpha's right during the first heat."

"Stop giggling," the teacher ordered of a group near the front.

"However, we now understand the membrane will tear naturally on its own after it weakens over several heats - which can be uncomfortable for some, especially male omegas - with minimal scar tissue. Or when an omega presents, a doctor can perform a simple incision with localized anesthesia."

Riku used his eraser to poke his stupid hollowed out egg shell with a sharpie scribble face. The eye had been drawn funny, making it look like it was winking. Drunk winking. He was supposed to cart it around with him everywhere to express upon them the important of parenthood. It still smelled like egg yolk, which wouldn't be very pleasant in a couple of days.

"-which led to the natural development of omega Commands, which are merely suggestive to most Alphas but near imperative between mated pairs-"

"If you can't take this seriously you can go stand in the hall," the teacher interrupted again.

Riku poked his egg again, and glanced over to see Kairi doodling in her notebook. Raft designs, it looked like. She saw him looking and pointed at one, eyebrow raised in question. He glanced to see what Sora thought and Sora... was asleep.

While the still way too cheerful woman went on about mated pairs and synchronizing cycles, Riku reached over and poked Sora's side. No reaction. He poked harder, and Sora jerked upright and sent his egg in its little box careening across the desk like a cardboard race car. Riku caught it just in time. Kairi snorted in laughter on his other side.

The film abruptly stopped. "Is there a problem back there?"

"Just preventing infantcide, Sir," Riku responded with a slight grin, holding up the box. The teacher sighed and hit play again. 

Sora snatched it back and settled his egg back on his desk. "It's okay Yolko."

"You named your egg Yolko?" Kairi whispered across Riku's desk. "Give mine a name!"

"Shelldon?" Sora suggested.

"Gross, no."

"Eggward?"

"Perfect!"

"Kairi, Sora, go stand in the hall."

Riku and their friends waited while the teacher chastised the two after class, then handed each of them their egg. "I charge twenty an hour for babysitting," he informed them. "Kairi, there's something on your skirt."

"Where?" She tried to look over her shoulder, then Selphie twisted her skirt slightly to see the stain. "It looks like blood," she remarked.

"Are you hurt?" Sora asked.

"I don't think so..." she checked her legs. "Maybe I sat in something."

Selphie took her egg and handed it back to Riku, then pulled her towards the bathroom. "We'll be right back," she called.

A moment later they came out with Selphie's cardigan tied around Kairi's waist. "We're going to the nurse's office," Selphie announced and practically dragged Kairi down the hall.

"Somethin' wrong?" Wakka asked.

"I don't know," she admitted. But she wouldn't let any of them into the nurse's office with her. She stayed in there a good long while, so long Tidus had to excuse himself to go home before his father got angry. Wakka offered to walk home with him. Selphie started her homework, but Sora kept fidgeting and glancing at the nurse's office door.

Their waiting was in complete vain, however, when a car pulled up and the driver got out to open the door for the passenger. "That's the mayor!" Selphie hissed, although Riku knew her better as Kairi's mom. She briskly entered the nurse's office, but was slower while gently leading Kairi out with her arm around the girl's shoulders.

"Kairi-?" Sora started to ask. Kairi didn't say anything, just looked a little pale.

"Sorry boys we've got a doctor's appointment to make." Riku knew that voice - the grown up 'everythings going to be okay' voice they used to make kids feel better.

Didn't they know it didn't work?

"She forgot Eggward," Sora said. Riku glanced down at the second egg box in his hand. For a moment he couldn't remember which was which until he noticed the wink.

"Eggward can have a sleepover with -"

"Dieggo." 

"You cant just name my egg," Riku protested, although he kind of liked it. It was better than Shelldon, anyway.

"Well I did so there."

"I have to get going, I'm late to gymnastics," Selphie sighed. "Bye guys."

"Bye," they both echoed as she headed out the door. Sora looked to Riku. "Wanna go to the island?"

"Sure, I can whoop your butt at swords." That earned him a scowl.

"I beat you just last week!"

"Two weeks ago," Riku corrected him. While his new muscles made winning easier through brute force, Sora's speed made him a difficult target. Even Wakka had trouble hitting him - although Riku thought throwing a ball was way too obvious of a move. It'd be nice to have the island to themselves again. It always used to be just them. Riku had shown Sora the hidden cave when they were tiny and they drew pictures in there all the time.

It still upset him when he saw Kairi and Sora's drawing of each other on the wall. Jealous, even. Why did Kairi draw a picture with Sora? Riku had been the first to suggest making friends with her.

"How many worlds do you think are out there," Riku asked absent mindedly as they made their way to the docks. "As many as there are stars?"

"That's a lot of worlds. How will we find Kairi's?" 

"We'll just have to search them all," Riku said, his heartbeat picking up and thudding against his ribs. He _had_ to go. He knew he had to find someone somewhere out there. No oceans... no borders.

A secret.

Sora smiled back at Riku as he jumped from plank to plank down the dock. "Sounds like an adventure!"

**Notes for the Chapter:**

> I wrote this at work on AO3 so if the formatting is weird let me know.
> 
> Special shoutout to Grayweathersby13 for commenting... actually spurred me to finish it LOL And as always thanks to my partner for being a soundboard.
> 
> Oh special note: I actually meant to make Riku's parents Lightning and Hope from FFXIII, mostlybecause a perfect example of omega husband and alpha wife... and my partner and I agree that Lightning has a weakness for cute things. So thaaaat I may go back and retcon. Its a stupid detail but explains Riku's personality a bit better. (But I understand if that age gap is a squick for some.)


	3. Chapter 3

Kairi seemed uncomfortable the next few days. When Sora asked if she had a stomachache, she said she didn't even though she was holding her stomach. But she wouldn't tell them what the doctor said - or the specialist she had to see after. Then she was fine, and Sora had forgotten about it. So Riku did too.

By the time they finally got a spare afternoon to go to the island and work on the raft, the eggshells had started to smell. They tucked the little things under a tree - in the shade at Sora's insistence - and separated to collect supplies from around the island.

Riku didn't know who built the original island, but they had left plenty of building materials around the forts and the shipwreck. He heard the ship had slipped through a portal from another world, as ships did when out on the seas, and run aground there. The survivors built the shelters from the missing half of the ship, until sheepishly realizing the mainland wasn't that far off and was occupied.

Surely their raft could find one such portal.

Riku found a tree that had fallen during one of last year's storms. The limbs were dry and broke off with a little bit of effort. It lifted easily, and Riku smiled in triumph to himself. With one arm he could carry it on his shoulder! Wait until Kairi and Sora saw - Sora would be so jealous.

As he hiked back across the sand, Sora and Kairi's voice just barely carried over the gentle lap of the water."-wouldn't mind going to visit."

"I'd like to see it too. Along with any other worlds out there! I want to see 'em all!"

"So what're we waiting for?"

"Hey," Kairi looked up at him as Riku cut in, "aren't you guys forgetting about me?" Sora turned around and Riku preened a bit as they both noticed the log he held. "So I guess I'm the only one working on the raft." He threw the log in Sora's direction who yelped and flailed as it barely missed him. Riku walked over and faced down Kairi, hands on his hips. She smiled sweetly up at him, mischief plain on her face. "And you're just as lazy as he is!"

Kairi giggled, hand behind her head and ducking down a bit. "So you noticed." She flashed him a sweet smile, and Riku felt his hackles smooth. "Okay, let's finish it together!" Riku flopped onto the sand next to Sora, bumping the skinny left with his sneaker. He needed to eat more.

"I'll race you!" She declared.

"Huh?" Sora sounded confused and Riku knew she was just cleverly goading them. Part of him approved, and another part felt annoyed that it worked so well.

"What, are you kidding?" he groaned, but braced his arm for the push off.

"Ready?" She cupped her hands to her mouth. "Go!"

Sand flew. Riku glanced over to see Sora grinning wildly, and Kairi behind them laughing. Riku beat Sora to the half finished raft but not by much. Kairi came up behind them a few seconds later. "I won. So you have to get the rest of the logs," Riku said smugly to Sora. Sora scowled and kicked the sand. "What else do we need to collect?" Riku looked to Kairi.

"Mmm... Rope. I remember we need a lot of rope. And a sail. And some other stuff." She motioned to the side hut nearby. "I wrote down the whole list. Riku you go find rope for the logs and start lashing them together. Sora can find the other items." She grinned at him teasingly. Sora grumbled, but followed after her while Riku laughed.

They lost their light as the sun began to set, and Kairi called it a day. The raft was coming along - a few boards had to be nailed in place to hold some of the logs together, but overall it looked like a sturdy raft.

"So Kairi's home is out there somewhere, right?" Sora asked, looking to Kairi. She leaned forward with a touch of a shrug.

"Could be," Riku answered for her, gazing out at the horizon. It was so close! "We'll never know by staying here."

"But how far can a raft take us?" Sora leaned out to look directly at him. With both of them up on the tree together, Riku felt content. This was how it should be.

"Who knows?" Riku waved his hand. The raft only had to get them to one of the portals he heard about. Then they'd find their way to another world. "if we have to, we'll think of something else." He was confident he could work it out, whatever came up. 

"So suppose you get to another world," Kairi started, then giggled a little, "What would you do there?" 

The question made Riku's thoughts stop short. He had someone to find. But it was a secret - even from Kairi and Sora. He had a promise to keep too, to keep Sora safe. "Well, I haven't really thought about it," he replied. It wasn't really a lie, he didn't know what he was supposed to do. Not yet, anyway. Getting off the islands was step one. He struggled to find a better answer. "It's just... I've always wondered why we're here on this island. If there are any other worlds out there, why did we end up on this one?" Why had Kairi come to this world? Maybe to be where she was now - here. With them. "And suppose there are other worlds..." He knew there were. "Then ours is just a little piece of something greater." He had made a promise. "So we could have just as easily ended up somewhere else, right?" He looked at the two of them to confirm his thoughts. They must have been destined to be here, together. For some reason. Like that man and that lady must have come to the island for something important.

Sora threw himself to lay down astride the trunk. "I don't know." Well that was Sora, Riku mused.

"Exactly." Riku unfolded his arms. Sora didn't know, but _he_ did. "That's why we need to go out there and find out. Just sitting here won't change a thing. It's the same old stuff. So let's go."

Kairi asked softly behind him, "You've been thinking about this a lot, haven't you?"

Riku turned to look back at her. "Thanks to you." He said honestly. Sora looked a little cross behind her, and Riku felt like rubbing it in a little. "If you hadn't come here... I probably never would have thought of any of this." And he may have forgotten his promise. Maybe Kairi was sent FOR Riku. "Kairi, thanks."

She gave a sheepish laugh. "You're welcome."

Maybe he was a little mean, goading Sora with the paopu fruit about Kairi as they left. He couldn't help it. Sora went red in his cheeks and flustered over his words. He wasn't even 100% sure Sora liked Kairi that way. When Sora tossed the paopu away, Riku felt a small surge of relief.

Sora hasn't even presented anyway, Riku mused to himself. He probably doesn't understand anything yet.

They were all at the dock ready to set off before they remembered their little eggs, left under the paopu tree.

They put them right back the next day, Sora building a little nest around them. "I'm going to be glad when school ends tomorrow," Kairi said, wrinkling her nose. "And we don't have to drag these things around anymore."

"Eggward is mad you said that," Sora replied with a put on air. "He is _offended_."

Riku gave him a push from behind. "Go find the rest of your supplies, you dolt," he ordered. "We set sail tomorrow, first thing after school is over."

Sora squawked at him. Riku grinned, enjoying poking Sora for a moment before they broke apart to gather up the remaining items. They raced - with Riku winning. He smirked widely at Sora, who comically slumped over in defeat. He didn't even seem to remember Riku teasing him AGAIN with the paopu.

"Don't you both have work to do?" Kairi scolded after their fourth race - tied two to two. Sora seemed to have perfected his path across the island.

"Sorry Kairi," they both said, and Sora yelled, "Jinx!" before running off. Riku rolled his eyes and went back to the raft to finish hoisting the sail and tying it off. Kairi helped, kneeling on the raft and stitching the cloth together tightly.

"Did you mean what you said?" Kairi suddenly asked. Riku looked down at her from where he had his legs locked around the mast.

"Did I mean what?"

"That the winner shares a paopu with me." She looked down at her stitching with intent.

Riku dropped from the mast. "You heard that huh?"

"It's a small island."

"I was just teasing Sora," Riku shrugged it off and looked up to view his handiwork. The sail should stay secured to the mast. "Paopus don't mean anything anyways. That's what claiming bites are for now."

"Even on people who aren't ABO?" Riku looked at her in confusion. She stood up and faced him. "A claiming bite won't work on me. The doctor said so."

Riku thought back to the previous week. "Is that why you went to the doctor?"

She made a face, her cheeks pink. "Sort of. I'm different. I know that. But why did you say that to Sora?"

Riku shook his head and turned to tug on the ropes to make sure they were secured. "To get him riled up. It was funny. I didn't really mean it though, sorry." He glanced back at her, and she was looked at him as if considering something. "I think we might need more rope. I'll go look."

He hunted some more down on the far side of the island. The sun was starting to sink in the sky when he dropped it off at the raft. Looking around, he saw Kairi and Sora were waiting on the boat dock for him and headed over. He was about to call out to them when he heard his name. He drew up short, and -

"Let's take the raft and go - just the two of us!"

Riku's chest felt tight. His thoughts tumbled over each other like fighting dogs, to the point he couldn't distinguish them. He found himself storming away to the little island where the paopu grew. When he looked over at the dock and saw the two small figures, one now standing, and his fists trembled. He shook himself to try and throw off the cloud hovering over him. His foot knocked into something, and when he glanced down, three marker drawn face smiled cheerily up at him on a nest of leaves.

Eggshell smashed under his sneaker.

**Notes for the Chapter:**

> Hmm.
> 
> I literally had a youtube video playing on mute at work to type all the dialogue properly. This is what happens when I get too much time on the reference desk. I had written the race out, but it was pretty dull and word for word so I ended up deleting it and it flowed a little better.


	4. Flashback

**Summary for the Chapter:**

> Mini chapter time!

__

__

"Did you hear?"

He lifted his eyes from his book to see his friend approaching from the long white hallway.

"Good morning to you too," he drawled, turning his gaze back to the textbook. "A fine day, is it not? How did you do on your evaluation yesterday? Yes I also believe gossip is the great collective downfall of good society."

An exaggerated eyeroll was his only response as his feet were nudged aside to make room on the seat. "Did you hear about that blonde girl in the next form?"

"What about her?"

"She's been expelled. The fourth Omega this semester!"

The words swerved on the page in front of him. He blinked hard and pulled the book closer to hide his reaction as his friend nattered on. "She presented after the stress of evaluations. It's a shame, she showed a lot of promise."

"A shame," he echoed.

Fingers blocked the words he wasn't reading and tugged the book down. "What's the matter Xehanort?"

His mind raced to grasp an answer that would work. "It's… depressing to think of all that training going to waste. Simply because of the body you're born with."

Eraqus nodded in agreement, before raising a hand in a careless sweeping motion. "The Masters are only looking out for them. She'll be placed with a good mate, and she'll be able to support the burden they carry with her training background."

Xehanort couldn't stop himself from pulling his legs in close to his body. A small silent sniff reassured him his blockers held. Eraqus took the motion as an invite for him to settle comfortably across from his friend with his own book.

"Keyblades take more strength than they have. No Omega can be a keyblade master."

**Author's Note:**

> Different worlds have different ways. And not all are kind.


End file.
